Pharmacokinetics of paracetamol after cardiac surgery.

Plasma concentration was measured after rectal and nasogastric administration of paracetamol 15 mg/kg to 28 febrile children aged between 9 days to 7 years who had undergone cardiac surgery. After equivalent doses, rectal administration in neonates and children on the first postoperative day was found to produce plasma concentrations below the therapeutic range with higher concentrations after nasogastric paracetamol on the second postoperative day. There was less variance in plasma paracetamol concentrations in neonates. Both plasma elimination half life and area under the plasma concentration time curve were significantly increased in neonates after suppository dosing compared with older children. There was no difference in antipyretic effect between the two routes of administration, but this was much lower than that previously reported in febrile children.

An unusual case of causalgia. Relevance to recent hypothesis on mechanism of causalgia.

Intravenous regional sympathetic block with guanethidine caused only limited improvement in a patient with longstanding causalgia. Lumbar sympathetic block with phenol also had little direct effect on the pain but completely abolished associated allodynia and vasomotor signs. Following sympathectomy the response to subsequent guanethidine blocks was enhanced. This improvement persisted even after 8 months when there was some return of the previous allodynia and vasomotor signs (to involve a smaller area than previously). The case would appear to have implications for a recently proposed hypothesis concerning the mechanism of pain in causalgia.

Acute gastric dilatation in an incarcerated hiatus hernia.

A case is reported of an unusual complication in which acute gastric dilatation occurred in an incarcerated hiatus hernia, resulting in left ventricular failure in the postoperative period. Failure to recognize this gave rise to concern when the patient re-presented for further surgery.

Pain-free injection in infants. Use of a lignocaine-prilocaine cream to prevent pain at intravenous induction of general anaesthesia in 1-5-year-old children.

A randomised, placebo-controlled, double-blind study was undertaken in 111 children between the ages of 1 and 5 years to assess the efficacy of EMLA 5% cream in the alleviation of venepuncture pain at intravenous induction of general anaesthesia using 27-gauge needles. Pain assessment was made by an operating department assistant using both verbal rating scale and visual analogue scale methods. Seventy-five children, of whom 24 were premedicated, were treated with EMLA cream and 36 with placebo, 14 of whom were premedicated. Significantly lower pain scores were recorded in the children treated with EMLA cream (verbal rating scale: premedicated p less than 0.05, unpremedicated p less than 0.001; visual analogue scale: premedicated p less than 0.0005, unpremedicated p less than 0.0002). No variation in analgesia was found for application times between 30 and 300 minutes and there were no serious side effects.

Peak density and distribution of ganglion cells in the retinae of microchiropteran bats: implications for visual acuity.

We have estimated the total number, distribution and peak density of retinal ganglion cells (RGCs) in retinal wholemounts of several species of microchiropteran (echolocating) bats. The estimates are based on counts of Nissl-stained, presumed RGCs. The total number of presumed RGCs varies among the species: from about 4,500 in Rhinolophus rouxi to about 120,000 in Macroderma gigas. In addition, in two species (Nyctophilus gouldi and M. gigas), the estimates are based on counts of positively identified RGCs retrogradely labelled with the enzyme horseradish peroxidase injected into the retinorecipient nuclei. In these two species, the numbers and distributions of retrogradely labelled RGCs and Nissl-stained presumed RGCs are very similar. In all six species studied, the peak-density regions of presumed (or positively identified) RGCs are located in the inferotemporal retinae, and the RGC isodensity lines tend to be horizontally elongated. However, the RGC densities in the high-density regions are only 2-4 times greater than those in the low-density regions in the superior retinae. The somal sizes of RGCs vary from 5 to 16 micron in diameter and are unimodally distributed. There is no indication of the existence of distinct morphological classes of RGCs. The axial lengths of microchiropteran eyes vary from 1.8 mm in R. rouxi to 7.0 mm in M. gigas. For all species the posterior nodal distance (PND) was assumed to be 0.52 of the axial length of the eye. This assumption is based on the analysis of published data concerning schematic eyes of nocturnal vertebrates. These derived values of the PNDs allowed us to calculate the retinal magnification factors and the number of RGCs per degree of visual angle. From these, the upper limits of visual acuity were derived on the basis of the assumptions of the sampling theorem. The estimated upper limits of visual acuity of the six species of echolocating bats vary from about 0.35 cycles/degree in R. rouxi to about 2 cycles/degree in M. gigas. This range is quite similar to the range of visual acuities in murid rodents.